Rhombic Cyclobutadiene with a Boryl/Amino-Substitution Pattern: Boryl Group Migration Induced by Reaction with Water

Abstract

The synthesis of a donor-acceptor cyclobutadiene featuring a boryl/amino-substitution pattern is presented together with its characteristic reactivity toward water. On the basis of the results of X-ray crystallography, theoretical studies, and spectroscopic analyses, the observed rhombic structure of the cyclobutadiene was attributed to a charge-separated electronic structure. Reaction of this boryl-substituted cyclobutadiene with water induced a characteristic migration of the boryl group, due to the Lewis acidity of the boryl-substituent.

Cyclisation of biscarbenoids – a novel mode of cyclobutadiene stabilisation

“…6 Exocyclic push-pull stabilisation, however, allows access to all-carbon CBDs, first in an early publication from Gompper and Seybold, 7 and more recently in a structurally-authenticated example from Yamashita and coworkers (VI, Scheme 1) bearing alternating diethylamino-and pinacolboryl-functionalities. 8 As a consequence of the contributing zwitterionic resonance structures, CBD VI features a rhombic C 4 moiety.…”

Prediction of the structural and spectral properties and reactivity of the silicon analogs of cyclobutadiene C4-nSinH4 (n=0-4) by density functional theory computations

“…So, this molecule participates as a ligand in various organometallic compounds such as cyclobutadiene tricarbonyl complexes [7]. As another application of this molecule, it is a part of different medicine structures [8]. In recent years, many scientists had tried to solve the instability and antiaromaticity problems of this annulene by entering silicon atoms in the structure of cyclobutadiene [9,10].…”

“…So, one can hope that the silicon analogs of this molecule would have had more applications than cyclobutadiene compound. In last decades, various attempts were done for preparation of these analogs [7][8][9][10][11], but its chemistry is very novel and needs more researches to complete the understanding their structures and applications. So, the present study aims at providing some useful information about the structural and spectral properties, reactivity, and natural bond orbital (NBO) population analysis of the cyclobutadiene molecule and its silicon analogs.…”